標題: Saturated flow boiling heat transfer and associated bubble characteristics of R-134a in a narrow annular duct
作者: Lie, YM
Lin, TF
機械工程學系
Department of Mechanical Engineering
公開日期: 1-十二月-2005
摘要: Experiments are conducted here to investigate how the channel size affects the saturated flow boiling heat transfer and associated bubble characteristics of refrigerant R-134a in a horizontal narrow annular duct. The gap of the duct is fixed at 1.0 and 2.0 mm in this study. The measured heat transfer data indicate that the saturated flow boiling heat transfer coefficient increases with a decrease in the gap of the duct. Besides, raising the imposed heat flux can cause a significant increase in the boiling heat transfer coefficients. However, the effects of the refrigerant mass flux and saturated temperature on the boiling heat transfer coefficient are milder. The results from the flow visualization show that the mean diameter of the bubbles departing from the heating surface decreases slightly at increasing R-134a mass flux. Moreover, the bubble departure frequency increases at reducing duct size mainly due to the rising shear stress of the liquid flow, and at a high imposed heat flux many bubbles generated from the cavities in the heating surface tend to merge together to form big bubbles. Correlation for the present saturated flow boiling heat transfer data of R-134a in the narrow annular duct is proposed. Additionally, data for some quantitative bubble characteristics such as the mean bubble departure diameter and frequency and the active nucleation site density are also correlated. (c) 2005 Elsevier Ltd. All rights reserved.
URI: http://dx.doi.org/10.1016/j.ijheatmasstransfer.2005.05.013
http://hdl.handle.net/11536/12994
ISSN: 0017-9310
DOI: 10.1016/j.ijheatmasstransfer.2005.05.013
期刊: INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
Volume: 48
Issue: 25-26
起始頁: 5602
結束頁: 5615
顯示於類別:期刊論文